Filter for purifying the air



2-1 19 June 27 H. WITTEMEIER FILTER FOR PURIFYING THE AIR Original Filed Jan. 5-, 1921 IN VENTOI? /%M77%W A TTDRNE K Patented June 21, 1927.

UNITED STATES HANS WITTEMEIER, OF BERLIN, GERMANY;

FILTER FOR PUBIF YING THE AIR.

Original application we January 5, 1921, Serial No. 435,288, and in Great Britain July as, 1915. Divided and this application filed March 15, 1924. Serial No. 699,600.

In many technical processes and plants the purification of the air plays an mportant part. In heating and ventilating plants the cleaning of the air is necessary for hygienic reasons; in turbo-generators, compressors and the like the air must be deprived of dust in order to secure reliability of operation which would be impaired by dirt that would rapidly collect in sensitive parts of the machines.

The only materials that were used hitherto for filtering purposes were substances whose structure or texture were such as ,to present the largest possible surface, coinined with a small resistance, to the air passing through them. Such substances are, for example, porous and granulated bodies, fibrous and textile materials, and, in a small measure, finely distributed liquids.

Hitherto the preference has generally been given to fibrous stufis in the form of filtering cloths. But these still have two serious drawbacks; In the first'place, the clogging up of the cloth by the dust results in a rapi increase of the resistance ofiered to the airpassing through it; and secondly, even if they are impregnated with a non-combustible agent they are not sufficiently proof againstfires, which are liable to occur, es-

pecially in electric generators. This draw-' back had to be met by providing special firepreventing flaps. f

These drawbacks are obviated by making the filtering members of layers of non-combustible bodies of an geometrical shape such as balls, cylindrica or prismatic rods of glass, porcelain, etc., which, in order to increase their adhesiveness, are coated by a non-evaporating liquid such as glycerine or the like.

The advantages ofiered by the new invention are as follows: The roneness'of the filter to become rapidly c ogged with impurities is removed, because the dirt-removing operation principally consists in 'repeatedly deflecting the innumerable air jets into whichthe whole air current is divided. The arrangement of the filter may be such that the untreated air first encounters a layer of comparatively large balls and then passes through additional layers of finer balls.

Another advantage is that the casing of the filter may be made of any space-saving a simple mechanical cleaning process is employed and the soiled filter material is always re-used after cleaning, whilst the socalled filter cloths had to be cleaned from time to time by-a chemical process and were worn out very much faster. The cells may be taken out and cleaned without taking out separately the filtering material.

This application is a divisional application of my U. S. Patent No. 1,521,57 5 granted December 30, 192 1, and the present invention relates specifically to a s ecific embodiment of the invention set fort in the foregoing patent. Y

The invention is illustrated in the accompanymg drawings in which Fig. 1 is a. front view partly in section, on line 1-1 of Fig. 2;

Fig. 2 is a horizontal section taken on line 2-2 of Fig. 1, with the right hand por tion shown diagrammatically.

Fig. 3 is a vertical section on line 3-3 of Fig. 2, of special form according to the invention some of the parts to the rear being omitted.

Fi 4 and 5 show different arrangements for c caning the filter bars of Figs. 1 and 2.

'Fi 6 is a separate view of one of the bars showmg the action of the air in respect thereto.

Similar characters of reference indicate corresponding parts throughout the various views. I

The dust-retainin bodies that are moistened with dust-retaining substance may also take the form of grating bars. An arrangement of this kind is shown in Figs. 1 and 5. To prevent dust, from accumulating on the bars they are scraped clean from time to time by special dust scrapers that are moved along the bars. A separate scraper may be provided from each bar, and each scraper may be arranged to be moved up and down by itself. Butthe arrangement may also be such that all the scrapers are connected to a common driving device by which they are moved up and down together. Another arran ement consists in providing a common s eet metal scraper composed of a sheet with slits through which the filter bars pass. To clean the bars the sheet metal scraper is simply moved up and down.

When the bars have been scraped clean, they must be provided with a fresh coating of dust-retaining agent. This is accomplished in accordance with the invention by attaching moistening devices to the scrapers by means of which the dust-retaining a cut such as a suitable viscous coating, as gycerine, is conducted to the various filter ars.

The moistening devices move up and down with the scrapers. When these latter are intheir bottom position, the tap or taps of the. moistening devices are opened so that thedust-retaining agent is imparted' to the filter bars during the upward motion of-the scrapers and when these scrapers reach their top position the said taps are closed again.

' Means may be provided by which the opening and closing of the taps is done automatically, and this means may consist of cams of the kind used on machine tools, such as a vertical planer in' which the work reciprocates.

The vertical bars a, a 6 b c, a are arranged in an opening in the brick wall d, the bars being placed in several rows one behind the other and all passing through a metal sheet e that is arranged to move up and'down in the said opening and serves as a scra er. To maintain a good scraping eflect, ownwardly extending rojections ma as indicate in Fig. 4, .or movable flaps f may be arranged at the underside of t e scraper sheet as shown in Fig. 5, springs (not shown) being provided that press the flaps a ainst the filter bars.

The ter bars are fixed at one end, namely their u per ends only, their lower ends being sus en ed in the air, so that the bars will yie d and no jammin of the late e will occur when it is move u and own.

The filter bars are all of angular cross section, so that when the air passes through in the direction indicated by the feathered arrow, eddies are formed, which favor the depositing of the impurities of the air on the filter bars, and especially the coarser dust.

One skilled in the art will recognize that this type of filter is intended for coarser dust.

Beneath the filter bars a special pit g is formed in the brick or stone wall, this pit being adapted to receive the dust scraped off the bars. The dust heap can be readily shoveled out of the pit when the door or flap g is turned down in the direction indicated bv the arrow. At the upper side be stamped out of the s eet.

flows from' the tank into the pipes h, is opened when the scraper sheet a is in its lowest position I, Fig. 3, but is closed when it reaches its highest position II, Fig. 3.

The said valve or cock is controlled by cams arranged on the wall at the points m, 'm, indicated in Fig, 1. In Fig. 1 cams m and m are shown projecting from wall at in such a manner as to engage a handle 1 on valve is. When the scraper is in its lowest posi tion I cams we engage handle r so as to open valve Ia and when it is raised to the up er position II the valve is rocked downwar y y ing operation is repeated. From the distributmg pipes 72. branch pipes at (Fig. 2) lead to theindividual filtering bars. 1

The reciprocatin vertical motion of the scraper sheet e an the system of pipes attached thereto may be arranged to be carried out continuously, or at certain intervals as required. Any suitable kind of drive may be employed; for illustrative purposes the handle 7' is shown which is lowered and raised to erfo'rm the scraping operation on p the filter ars.

From the'foregoing it will be seen that scrapers are provided in connection with the scrapers bein provided on any concave portion of filter ars. It will be noted that the filtering bars are arranged substantial] in one direction, with the same sides of al the bars windward. The scrapers serve to scrape ofi the dust that has accumulated and at the same time serve to equalize the viscous coating applied to the bars. The scrapers may be operated automatically or by hand.

Instead of providing all of the bars with scrapers, several of the same may be provided and the scrapers may be made interchangeablo to all the bars. The scrapers may be operated during the air flow passing through the filter or when the air flow has been stopped the scrapers may be operated for the purpose of cleaning only.

I claim:

1. A filter comprising a filter bar and means for scraping the same.

2. A filter comprisinga filter bar hollowed on one side and means in the hollow side ghereof for scraping the collected dust thererom. I

cam m and again closed .until the scrap- 3. A filter "com rising a bar having a viscous coating an scraper therefor for removing the accumulated dust and equalizing the coating on the concave side ofithe filter 4. A filter comprisin a bar, a scraper thereon for simultaneous y removing the dust and supplying a viscous coating to the filter.

5. A filter comprising a filter bar and means for supplying the filter bar with a viscous coating, and means for moving said coating means along the filter bar.

6. A filter comprisin a plurality offilter bars held at one end, an a scraper for scraping all of said bars simultaneously. I

7. A filter comprising a pluralit of filter bars held at one end, a scraper or scraping all of said bars simultaneously, and

means for providing the bars with a viscous coating simultaneously therewith.

In testimony that I claim the foregoing as my invention, I have signed my name hereto.

HANS WITTEMEIE R. 

